Embodiments of the present disclosure generally relate to monitoring of subsea structures, and more specifically to monitoring of pressure and/or stress in risers, pipes, and flow-lines of the subsea infrastructure.
In subsea hydrocarbon production, risers are utilized to deliver fluid from the subsea well to a collecting asset, such as a production vessel or an injection fluid to the subsea well from the production vessel. Also, during subsea drilling a riser is used to contain the drill pipe and provide a return path for drilling fluid. Typically, risers extend from a seabed to the surface and are subject to bending, twisting, and tensional forces due to currents and movements of the production vessel. Depending on flow parameters such as flow rate, temperature, and consistency, the risers can experience stress build-up due to pressure difference between ambient and a flow channel. In order to ensure effective operation of risers, it is beneficial to continuously monitor the stress experienced by the risers. Also, identifying pressure and/or stress variations aids an operator in ensuring efficient transfer of oil from the subsea well to the collecting asset.
Occasionally, strain sensors such as strain gages and fiber Bragg sensors are employed to sense mechanical stress in the risers. Additionally, pressure sensors may be employed to measure pressure in the flow-lines and the risers. Use of the strain sensors and/or pressure sensors generally entails mechanical coupling with the flow-lines and risers. Extended use of these sensors results in loss of strength of mechanical adhesion of the sensors. Also, the sensors may be subject to harsh environments for extended periods of time. In addition, repair or replacement of sensors may be a challenging task.
Furthermore, the riser and/or the flow-line are generally designed and deployed with a fixed number of sensors disposed at determined locations. However, it may be desirable to either increase the number of sensors on the riser and/or flow-line, or vary the locations of the sensors during the lifetime of the riser and/or flow-line. However, varying the number and/or location of the sensors is an expensive and laborious task.